Upgrade to Dropwizard Metrics 3.2.6

Closes gh-11544

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -45,7 +45,7 @@
 		<couchbase-cache-client.version>2.1.0</couchbase-cache-client.version>
 		<derby.version>10.14.1.0</derby.version>
 		<dom4j.version>1.6.1</dom4j.version>
-		<dropwizard-metrics.version>3.2.5</dropwizard-metrics.version>
+		<dropwizard-metrics.version>3.2.6</dropwizard-metrics.version>
 		<ehcache.version>2.10.4</ehcache.version>
 		<ehcache3.version>3.4.0</ehcache3.version>
 		<embedded-mongo.version>2.0.0</embedded-mongo.version>